Numerical calculation of marangoni convection in a rectangular open boat

Numerical calculations of the flow caused by thermocapillary forces at the free surface in NaNO₃ and Si melts in an open boat geometry have been carried out. The results agree well with measured flow velocities in model experiments for crystal growth configurations with NaNO₃ melts. For Si melts a transition to a more complicated multiple eddy flow occurs. The projection-iteration method used for the calculations is much more effective than the finite difference methods applied until now and is especially advantageous for more complicated flow patterns.     

Eigenschaften und Kristallzüchtung von Oxiden mit Halbleiter-Metall-Übergängen

This review reports the possibilities of crystal growth for oxides of vanadium and titanium having semoconductor-to-metal transitions. The favoured methods of crystal growth, chemical transport reactions, and the flux melts are discussed in detail.     

On quasilinear parabolic evolution equations in weighted L p -spaces

In this paper we develop a geometric theory for quasilinear parabolic problems in weighted L _p -spaces. We prove existence and uniqueness of solutions as well as the continuous dependence on the initial data. Moreover, we make use of a regularization effect for quasilinear parabolic equations to study the ω-limit sets and the long-time behaviour of the solutions. These techniques are applied to a free boundary value problem. The results in this paper are mainly based on maximal regularity tools in (weighted) L _p -spaces.     

Electrical and optical simulations of a polymer‐based phosphorescent organic light‐emitting diode with high efficiency

A comprehensive numerical device simulation of the electrical and optical characteristics accompanied with experimental measurements of a new highly efficient system for polymer‐based light‐emitting diodes doped with phosphorescent dyes is presented. The system under investigation comprises an electron transporter attached to a polymer backbone blended with an electronically inert small molecule and an iridium‐based green phosphorescent dye which serves as both emitter and hole transporter. The device simulation combines an electrical and an optical model. Based on the known highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of all components as well as the measured electrical and optical characteristics of the devices, we model the emissive layer as an effective medium using the dye's HOMO as hole transport level and the polymer LUMO as electron transport level. By fine‐tuning the injection barriers at the electron and hole‐injecting contact, respectively, in simulated devices, unipolar device characteristics were fitted to the experimental data. Simulations using the so‐obtained set of parameters yielded very good agreement to the measured current–voltage, luminance–voltage characteristics, and the emission profile of entire bipolar light‐emitting diodes, without additional fitting parameters. The simulation was used to gain insight into the physical processes and the mechanisms governing the efficiency of the organic light‐emitting diode, including the position and extent of the recombination zone, carrier concentration profiles, and field distribution inside the device. The simulations show that the device is severely limited by hole injection, and that a reduction of the hole‐injection barrier would improve the device efficiency by almost 50%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Einwirkung elektrischer Wellen auf Kolloide

Zusammenfassung Bei Behandlung von Kolloiden im hochfrequenten elektromagnetischen Feld werden die Eigenschaften derselben ver?ndert, z. B. Farbe, Viskosit?t, Koagulationswert, Kataphorese und Leitf?higkeit.     

Die Adsorption als Vorstufe der chemischen Verbindung,untersucht durch Adsorptionsmessungen am Zirkonoxydhydrogel

Ohne Zusammenfassung Die Mitteilung mu?te wegen Raummangels stark gekürzt werden. Wegen verschiedener experimenteller Einzelheiten siehe Dissertation Hellmuth Wilke (G?ttingen 1923).